Dental handpiece



Patented Aug. 17, 1926.

UNITED STATES PATENT QFFlCE.-

LAURETZ BREDENBERG ANDRESEN, OF MINNEAPOLIS, MINNESOTA, ASSGNOR T0 M. F. PATTERSON DENTAL SUPLY COMEANY, OF ST. PAUL, MINNESOTA, A COR- PORATON 01'* LLINOIS.

DENTAL -IANDPIECE.

llpplcation filed March 22,v 1924. Serial No. '701,127'.

This invention relates to improvements in what are known in the dental art as handpieces. These hand-pieces are employed in connection with the usual dental engines and are adapted selectively to have mounted therein diii'crent dental tools. The present invention relates to a hand-piece. in which there is a decided reduction in they number of parts with relation to the present forms and in which a simple and easily operable device is provided for releasing the tool from, or locking it in, its operative position in the hand-piece. rThe member which operates the tool-clutch in this novel structure may bein axial alinement during operative use of the hand-piece so that the nice-ty of balance of the piece is not lost and the po- -sition of the member itself does not interfere with accurate and delicate manipulations. Further, the releasing position of the locking member is one that is readily,7 visually noted. This novel clutch-operating member is one which may be manipulated by a linger of the same hand which is using the hand-piece. Tins, a given tool may be released from the hand-piece and another one inserted'from the usual rack, wherein the tools are held with their stems upstanding,

without the employment of the other hand of the dentist with the resultant expedition of the dental operation being carried on and with lessened likelihood of infection due to handling of the newly inserted tool. Another improvement in this hand-piece consists in providing the thrust bearings to preventend-play at a position away from the toolend of the hand-piece where these bearings are exposed to pumice, etc. either with or without the admixture of saliva. Further, a means for the adjustment of these end-thrust bearings is provided which is operable from the exterior of the hand-piece, thus obviating the usual demounting of the hand-piece fer such adjustment.

The object of the invention there fore is to provide an improved dental hand-piece.

Other objects of the invention will appear from the following description and the accompanying drawings and will be pointed out in the annexed claims.

ln the drawings there' has been disclosed a structure'designed to carry out the objects of the invention, but it is te be understool that the invention is not confined to the Figure 3 is a view in detail of the clutch- Y end of the shaft without the casing, the shaft being turned at a right angle to its position in Figure 2;

Figure Ll is a detail view of the linking member in the same position shown iu Figure 1 but turned at a right angle thereto;

Figure 5 is a transverse sectional View on the line 5 5 of Figure 2; l

Figure 6 is a longitudinal sectioiial view of the drive-end of the shaft witha modified form of locking member mounting; and

Figure 7 is a longitudinal sectional view of a still further modified form of the locking member and mounting.

In the selected embodiment of the invention here shown, there is illustrated a dental hand-.piece of the general type shown in applicants prior co-pending applica-tion Serial Number 674,277, filed November 12, 1923.

The hand-piece here shown includes a casing 11 of cylindrical form having an annular shoulder 12 connectedintegrally by the neclr 13 to the annular head 14 which is interiori?,v1 threaded to receive in threaded engagement the reduced end 15 of the plug 16 which functions as bearing for the drive-shaft. The drive-shaft is preferably made in three parts connected for simultaneous rotation. rlhese are the stem 17, the spindle 18, and the clutchcarrier 19.

The spindle 18 has its end portion toward the drive axially recessed and interiorly threaded to receive the reduced end portion 21 of the stem 17 in threaded engagement. A thrust collar 22 is closely fitted upon the reduced stein-portion 21 and abuts against the end of the spindle 18 upon vone uf its side faces while the other side face abuts against the annular shoulder' 23 of the .--tem 17. A thrust-bearing 24, preferably7 a fiber 4 pulley 27 is provided with an intcriorly threaded hub for engagement with the exteriorly threaded drive-end portion oi'l lhe stein 17 of the shaft of this novel hand-piece. The hub of the pulley, toward the tool-end. is formed with an integral axially projecting flange Q8 adapted to bear against the other thrust bearing 29 mounted upon the stem 17 between the flange 98 and the adjacent end of the shoulder Q6 of the bearing plug 16. The pulley is maintained in its threaded adjusted position upon the stern 1i' by means of the set screw 31.

The end thrust upon the shaft in an axial direction toward-the drive-end of the shaft is communicated to the thrust collar 22 by the end of the spindle 18 and is taken up by the bearing 24 while the end thrust in the opposite direction is taken up by the engagement of the flange Q8 of the pulley against the thrust bearing 29. Dental hand-pieces are commonly provided with bearings to take up thrust in both directions but at least one of them is usually placed adjacent the tool-end with the result that puinice and other cleaning or grinding materials enter the bearings with or without the admixture of saliva and wear is excessive. In this present construction it will be noted that both these thrust bearings are well away lfrom the tool-end and are not exposed to such excessive wear. Another decided disadvantage in present hand-pieces is that any adjustment of the usual thrust-bearings involves partial demounting of the hand-piece to give access to the usual adjustment. In this novel hand-piece, the adjustment may be quickly and simply made by backing off the set screw 31 to permit rotation of the pulley 27 whereby movement of the shaft with relation to the bearing plug 16 and its thrust bearings 24 and 29 is obtained.

Another phase of this invention resides in the novel means for operation of the clutch which grips the different tools commonly employed in dental work. These tools are of various kinds such as burrs, grinding wheels, cutting wheels, and each is provided with the usual tool-stem 32 which is adapted to be gripped by a chuck or clutch commonly carried by these hand-pieces. It is desirable that the clutch and its operative connections be of few parts which are simple and positive in operation and preferably operable by the fingers of the hand which holds the instrument so that one tool may be released and another picked up from the tool-rack without handling of the new tool.

In this novel hand-piece, the chuck or clutch is borne by a portion of the driveshaft such as the clutch-carrier 19. rEhe drive-end of this carrier 19 is centrally recessed to receive in threaded engagement the adjacent reduced threaded end of the spindle 1S by means of which the carrier is secured to the spindle for rotation therewith. The portion 33 of the carrier, intermediate this reduced threaded end and the nose-end portion 84 is provided with a median, transverse slot within which is seated the clutch comprising the two co-acting` similar jaws and 36. These complementary jaws have their greatest periphery at an intermediate portion thereof as indicated in Figures l and 2. A sleeve 37 is fitted to a portion 33 of the carrier part of the shaft and extends from its shoulder 38 over the major portion of the slot in order to retain the jaws in workingposition. Furthermore, this sleeve 37 provides jaw-fulcrums at said intermediate peripheral jaw-portions for the working movements of the jaws in gripping and releasing' a tool, that is, the jaws are provided with an external bearing against opposite portions of the inner annular face of the sleeve. The drive ends of the jaws are symmetrically formed to provide substantially a conical cavity for the reception of the conical working end 39 of the clutch-operating` rod 41. This conical end 39 is provided upon a tip 42 secured to the tool-end of this rod 41. The nose or tool-end of the jaws are formed to provide a substantially annular recess 43 for the gripping reception of a tool by means of the usual tool shank or stem 32. lWhen the rod 41 is pressed axially toward the nose-end of the hand-piece, vas is shown in Figure 17 the conical end 39 is thrust within the jaw-cavity with the result that the nose-end of the jaws are forced toward each other effectively to grip the shank or stem 32 of a tool whereby the tool is operatively held for rotation with the driveshaft. W'hen the pressure upon the rod 41 is released, the resiliency of the metallic aws forces the conical end 39 toward the driveend and thus permits release of the clamped tool stein. A radial bearing for this toolend of the shaft may be provided by the bearing sleeve 44 carried by the inner face of the nose-cap 45, secured to the casing 11 at its tool-end.

Means are provided at the drive-end of the hand-piece for the movements of this clutch-operating rod 41. The preferred form is shown in Figures 1, 2 and 4. The rod 41 extends from its conical end 39 through an axial recess in the spindle 18 and stem 17, and preferably does not extend to" the end of the shaft-stem 17. This end of the stem 17 is formed with a concave endface to receive a Cam device which may beoperated inwardly to thrust-the rod. An interiorly threaded collar 46 is adjustably mounted upon the exteriorly threaded end portion of the stem 17 and may be retained in fixed adjusted position thereon by the set screw 47. A pair of vears 48 project from the collar 46 in spaced axial parallelism and provide a bearing for the pivot pin 49 upon which is mounted the cam 51. This cam is substantially.disk-shaped with a cam-linger 52 adapted to extend operably within the concave end of the stem 17 so as inwardly to thrust the rod 41 when turned to the position shown in Figure 1. A convenient means of manipulation of this cam is provided by the knurled handle 53 connected by the shank 54 to the cam 51. When the cam handle is turned out of axial alinement with the rod 41, as shown inv Figure 2, the inward thrust is removed from the rod 41 and it is permitted to release the tool shank from the jaws.

The major portion of the casing 11 may be covered by a sleeve 55 of any of the usual grip materials such as vulcanite while a shouldered annular cap 56 may be fitted about the casing 11 toward the drive-end of the shaft and be interiorly threaded for engagement with the external threads upon the bearing plug 16 as is shown in Figure 1.

ln the modified form of rod-operating member shown in Figure 6, the pivot pin 49 of the cani 51 is operatively borne by the two spaced ears integrally formed upon the terminal plug 57 received within the threaded axial recess of the elongated hub 58 of the pulley 27. rlhe cam-carrying plug may be held in adjusted position by means of the set Screw 59 similarly to the set screw 47 of the preferred form shown in Figure 1. In this modified form the plug 57 is terminally concaved to receive the cam-finger 52.

In the modified form shown in Figure 7, the cam 61 is spheroidal with a finger 62 adapted to be projected within the concaved end of the shaft-stem 17 in a similar manner to that shown in Figure 1. This form is in the nature of a universal joint and the operative swinging ofthe cam handle 53 is not limited to a two-direction swing as is the case in a pivot mounting. A sleeve- 63 is mounted in threaded engagement upon the externally threaded end of the stem 17 and has a terminal socket for thev retentive reception of the spheroidal cam 61.

In the case of all of these forms of rodoperating devices, the mounting of each cam is adjustable and may be held in such position by the set screws 47. By changing the position of the collar 4G or the plug 57 or the socketed sleeve 63, the operative travel of the conical end 39 of the clutch-operating 1. In a dental hand-piece, the combination of a casing, a hollow drive-shaft rotatably borne therein and extending substantially the lengt-h of the hand-piece, a clutch con- 'nected to the shaft adjacent the tool-end and adapted to demountably to engage a tool, clutch-operating means movably borne within the shaft, an operating member for said means movably carried by the shaft externally of the casing and adapted for movement into axial alinement with the shaft to Vcause the clutch to assume tool-gripping position and for movement out of said axial alinement to cause the clutch to assume toolreleasing position.

2. In a dental hand-piece, the combination of a casing, a hollow drive-shaft rotatably borne thereinV and extending substantially the length of the hancl-piece, a clutch connected to the shaft adjacent the tool-end and adapted demountably to engage a tool, clutch-operating means movably borne within the shaft, and an operating member for said means pivotally mounted upon the shaft externally of the casing,said member being adapted to be swung into axial alinement with the shaft to cause the clutch to assume tool-gripping position or swung out of such alinement to cause the clutch to assume toolreleasing position.

3. In a dental hand-piece, the combination of a casing, a hollow drive-shaft rotatably borne therein and extending substantially the length of the hand-piece, a clutch connected to the shaft adjacent the tool-end and adapted demountably to engage a tool, a clutclioperati1ig rod movably borne within the shaft and ext-ending to a point adjacent the other-end of the shaft, a cam positioned at the drive end of the shaft for operating the rod, and an element mounted on the shaft at its drive end and from which the cam is supported to adapt it to be operated to cause the clutch selectively to assume a tool-gripping or tool-releasing position, said supporting element being adjustably mounted upon the shaft whereby the operative connection between said cani and clutch may be adjusted to permit the clutch togrip or release differently sized tools.

4. In adental hand-piece, the combination of 'a casing, a hollow drive-shaft rotatably borne therein and extending substantially the length of the hand-piece, a clutch oon.- neeted to the shaft adjacent the tool-end and adapted demountahly to engage a tool, a eluteh-operating` rod movably borne within the allait and extending* to a point adjacent the other end of the elialit. and a cam device operavy Carried by the shatt adjacent its drive end externally of the easing' and adapted to operate the rod to Cause the elutehto assume tool-gripping or tool-releasing positions.

5. ln a dental hand-piece, the combination of a casing, a shaft rotatably mounted therein7 a plurality of Complementary jaws5 the shaft being' radially Slotted and the jaws mounted therein, the Complementary jaws having.;` their greatest periphery at an intermediate portion thereof, a Sleeve'embracing the slotted portion of the shaft at Said intermediate peripheral jaw-portions to provide a tulcrum for operative movement of the jaws.

In witness whereof, I have hereunto set my hand this 19th day of March 1924.

LAURITZ BREDENBERG ANDRESEN. 

